This invention generally pertains to reservoirs. More specifically, the present invention relates to a compressible fluid reservoir having a variable working volume and a method for its use.
The invention is particularly applicable to a reservoir for storing a pressurized gas wherein the working volume of the reservoir can be selectively changed in order to assure that a desired quantity of gas at a desired pressure is stored in such working volume. However, it will be appreciated by those skilled in the art that the invention has broader applications and may also be adapted for use in many other environments where the storage of fluid under pressure is required.
Pressurized fluid reservoirs for both liquid and gas are known. However, all such reservoirs have a constant or fixed storage volume. In a situation where differing predetermined amounts of gas, or other compressible fluid need to be stored at differing predetermined pressures, the provision of only one reservoir having a fixed storage volume is inadequate. Several sizes of reservoirs would have to be provided in order to allow the approximately correct size to be used when a compressible fluid needs to be stored at differing predetermined volumes and at differing predetermined pressures.
Hydropneumatic or gas-oil accumulators are widely used in industry. These devices provide a smooth even flow of a liquid on demand at a relatively constant pressure thus reducing and possibly eliminating pulsations in liquid lines such as oil or hydraulic fluid lines. The primary use of accumulators is to store a liquid under pressure and the primary use of the stored energy is to supply power at peak system demand. This permits the use of smaller pumps in a system to recharge the accumulator during idle cycle time. In larger accumulators for central hydraulic systems, there is oftentimes no barrier between the pressurizing medium and the system liquid. In the other types of accumulators, a separator is provided between the pressurizing medium, i.e. a gas, and the liquid which is meant to be pressurized. Such liquid is generally an oil, water, or the like. However, accumulators similarly are not reservoirs having variable storage volumes for holding a compressible fluid since the object of these devices is to store a liquid under the pressure provided by a gas.
Conventional reservoirs also do not allow a compressible fluid which is initially stored at a relatively high pressure to be reduced quickly in pressure once the compressible fluid begins to flow out of the reservoir by enlarging the storage volume of the reservoir as the compressible fluid continues to flow. This would allow an initial release of compressible fluid at a relatively high pressure and a continuing flow of fluid at a rapidly decreasing pressure. Such fluid flow is considered to be advantageous in certain processes such as gas injection molding of thermoplastic materials.
Accordingly, it has been considered desirable to develop a new and improved reservoir for a compressible fluid which would overcome the foregoing difficulties and others and meet the above-stated needs while providing better and more advantageous overall results.